Engine blocks (cylinder blocks) may include one or more cylinder bores that house pistons of an internal combustion engine. Engine blocks may be cast, for example, from cast iron or aluminum. Aluminum is lighter than cast iron, and may be chosen in order to reduce the weight of a vehicle and improve fuel economy. Aluminum engine blocks may include a liner, such as an aluminum or cast iron liner. Aluminum liners may be cast-in to the engine block. Aluminum engine blocks that are liner-less or that have cast-in aluminum liners may include a coating on the bore surface. The coating (e.g., a steel-based, thermally sprayed coating) may reduce wear and/or friction.
Mechanical roughening may be used to prepare the surface of the engine bore to receive the coating so that the adhesion between the coating and substrate is sufficient to withstand manufacturing and operating loads. For example, a series of square grooves may be cut into the substrate using a side cutting end mill. After the grooves are formed, the tops may be deformed with a swiper (e.g., a rotary swage-wiper) to produce an undercut. The resulting profile may have dovetail-shaped peaks with sharp corners, which can lead to oxidation.